CVE-2023-32423: Apple Safari Buffer Overflow Vulnerability

CVE-2023-32423 Overview

CVE-2023-32423 is a buffer overflow vulnerability in Apple's web content processing components. Processing maliciously crafted web content may disclose sensitive information from process memory. Apple addressed the issue with improved memory handling across multiple operating systems and Safari. The flaw affects iOS, iPadOS, macOS Ventura, watchOS, tvOS, and Safari. Exploitation requires user interaction, such as visiting an attacker-controlled webpage.

Critical Impact
A remote attacker can craft web content that triggers a buffer overflow in WebKit-based rendering, leading to disclosure of sensitive in-process memory on Apple devices.

Affected Products

Apple Safari (versions prior to 16.5)
Apple iOS and iPadOS (versions prior to 16.5)
Apple macOS Ventura (versions prior to 13.4), watchOS (prior to 9.5), and tvOS (prior to 16.5)

Discovery Timeline

2023-06-23 - CVE-2023-32423 published to the National Vulnerability Database (NVD)
2025-03-20 - Last updated in NVD database

Technical Details for CVE-2023-32423

Vulnerability Analysis

The vulnerability is classified as a buffer overflow [CWE-120] affecting Apple's web content processing stack. When the affected component processes crafted web content, an out-of-bounds memory access occurs during parsing or rendering. The condition allows adjacent memory to be read or referenced beyond the intended allocation. The result is disclosure of sensitive information that resides in the renderer process address space. Apple resolved the issue through improved memory handling in the affected components.

Root Cause

The root cause is improper validation of buffer boundaries during web content processing. Apple's advisory describes the fix as "improved memory handling," indicating that the original code performed memory operations without enforcing strict size constraints. This class of defect commonly stems from missing length checks on attacker-controlled inputs delivered through HTML, CSS, or JavaScript constructs.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker hosts a malicious webpage or embeds crafted content into a site that the victim visits using a vulnerable Apple browser or WebKit-enabled application. When the renderer processes the content, the overflow triggers and leaks memory contents to the attacker-controlled context. The vulnerability does not directly grant code execution, but disclosed memory may contain session tokens, addresses defeating ASLR, or other sensitive data that aids follow-on exploitation.

No public proof-of-concept code or verified exploitation samples are available for this CVE. Refer to the Apple Security Advisory HT213757 for vendor-published technical context.

Detection Methods for CVE-2023-32423

Indicators of Compromise

Unexpected crashes or memory faults in Safari, com.apple.WebKit.WebContent, or other WebKit-hosted renderer processes following navigation to untrusted sites.
Outbound connections from end-user Apple devices to newly registered or low-reputation domains immediately preceding renderer instability.
Browser telemetry showing repeated reloads of the same crafted URL across multiple users.

Detection Strategies

Inventory all Apple endpoints and identify versions of iOS, iPadOS, macOS Ventura, watchOS, tvOS, and Safari that predate the fixed releases (16.5 / 13.4 / 9.5).
Correlate web proxy logs with endpoint crash reports to identify URLs associated with renderer faults.
Hunt for anomalous child processes or memory dumps generated by WebKit components on managed macOS fleets.

Monitoring Recommendations

Centralize macOS unified logs and Safari crash diagnostics for retrospective analysis of WebKit faults.
Monitor DNS and HTTP egress for traffic to known malvertising and exploit-kit infrastructure targeting Apple browsers.
Track patch compliance on mobile and desktop fleets through mobile device management (MDM) reporting against the minimum fixed versions.

How to Mitigate CVE-2023-32423

Immediate Actions Required

Update affected devices to iOS 16.5, iPadOS 16.5, macOS Ventura 13.4, watchOS 9.5, tvOS 16.5, and Safari 16.5 or later.
Push the updates through MDM to accelerate deployment across managed fleets.
Restrict browsing on unpatched devices to trusted internal resources until updates are applied.

Patch Information

Apple released fixes in iOS 16.5, iPadOS 16.5, macOS Ventura 13.4, Safari 16.5, watchOS 9.5, and tvOS 16.5. Vendor advisories are available at Apple Security Advisory HT213757, HT213758, HT213761, HT213762, and HT213764.

Workarounds

Disable JavaScript for untrusted sites in Safari preferences where patching is delayed.
Use network-level web filtering to block known malicious and uncategorized domains for users on vulnerable browser versions.
Enforce Lockdown Mode on high-risk user devices running iOS 16 or macOS Ventura to reduce WebKit attack surface.

bash

# Verify installed Safari version on macOS
mdls -name kMDItemVersion /Applications/Safari.app

# Confirm macOS build meets minimum patched release
sw_vers -productVersion   # Expect 13.4 or later